--Disease Characteristics-- Histologically confirmed adenocarcinoma of the prostate Androgen independent with at least 1 bone lesion that is felt to be associated with metastatic disease Refractory disease must be demonstrated after the withdrawal of flutamide, nilutamide, bicalutamide, or any other antiandrogen Clinically progressive disease for at least 1 month documented by rising PSA levels, at least 1 new metastatic deposit on Tc-99 bone scintigraphy, increasing measurable disease, or new areas of malignant disease Patients with PSA-negative disease (i.e., PSA less than 10 ng/mL) must have positive CT scans of soft tissue disease that can be used for disease staging, bone scan, or some other form of documentable disease progression (i.e., rising carcinoembryonic antigen, prostatic acid phosphatase) Testosterone in the range expected for castrated males No brain metastases or primary CNS malignancies No unresolved acute local complications that require urgent local medical therapy (such as severe bone pain, spinal cord compression, or urinary flow obstruction) --Prior/Concurrent Therapy-- Biologic therapy: Not specified Chemotherapy: No prior ketoconazole for prostate cancer Endocrine therapy: See Disease Characteristics Treatment with LHRH agonist must continue for those patients who have not undergone surgical castration If LHRH agonist has been discontinued, it must be reinstituted with documented disease progression At least 4 weeks since prior hormonal therapy other than LHRH agonist and recovered Radiotherapy: Prior radiotherapy to the prostate allowed At least 4 weeks since prior radiotherapy and recovered Surgery: Prior radical prostatectomy allowed At least 4 weeks since prior surgery and recovered Other: At least 4 weeks since other prior anti-cancer therapy and recovered No prior transfusion with strontium chloride Sr 89 and/or samarium Sm 153 lexidronam pentasodium No concurrent phenytoin, theophylline, cisapride, triazolam, astemizole, loratadine, rifampin, isoniazid, erythromycin, terfenadine, midazolam, alprazolam, atorvastatin calcium, cerivastatin sodium, dofetilide, lovastatin, pimozide, simvastatin, or sirolimus No concurrent drugs that decrease gastric acid output or increase gastric pH (e.g., antacids, cimetidine, ranitidine, or antimuscarinics) No concurrent warfarin --Patient Characteristics-- Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Greater than 3 months Hematopoietic: Granulocyte count at least 1,000/mm3 Hemoglobin at least 8.0 g/dL (pretreatment transfusion allowed, provided hemoglobin is maintained for more than 30 days without additional transfusions and/or an active source of bleeding is identified and treated) Platelet count at least 75,000/mm3 Hepatic: Acute care panel (i.e., electrolytes, BUN) and urinalysis normal Bilirubin no greater than 1.2 mg/dL ALT less than 2.5 times upper limit of normal AST less than 2.5 times normal Renal: Creatinine no greater than 1.5 mg/dL and no proteinuria present OR Creatinine clearance greater than 40 mL/min and proteinuria less than 500 mg/day (proteinuria not an exclusion for patients with stents in place) Cardiovascular: No history of unstable or newly diagnosed angina pectoris No myocardial infarction within the past 6 months No New York Heart Association class II-IV congestive heart failure Pulmonary: No chronic obstructive lung disease requiring oxygen therapy Neurologic: No uncontrolled seizure activity No history of seizures within the past 10 years Other: No other prior malignancies within the past 2 years except nonmelanoma skin cancer or carcinoma in situ of the bladder No other life-threatening illnesses No untreated infection HIV negative Willingness to travel from home to NIH for follow-up visits